Question

Assess the significance of zero-padding in the application of DFT to signal analysis. Zero-padding is crucial for

• A. Decreasing the resolution of the DFT
• B. Increasing the frequency resolution of the DFT
• C. Reducing the computational time needed for DFT calculations
• D. Directly enhancing the amplitude of the signal components

Hint:

Use zero-padding before DFT to get a more refined frequency spectrum. It improves visual clarity and helps locate frequency peaks more precisely.

Answer 1

The Correct Option is B

Zero-padding is a signal processing technique where additional zeros are appended to the end of a time-domain signal before applying the Discrete Fourier Transform (DFT). This does not change the actual frequency content of the signal but improves the frequency resolution in the spectral representation.
Explanation:

• The DFT of a signal with \( N \) samples gives \( N \) equally spaced frequency bins.
• When zero-padding is applied, the number of DFT points increases (e.g., padding a 64-sample signal to 256 samples).
• This provides a finer spacing between frequency bins, effectively improving the frequency resolution.
• However, it does not increase the actual information content—only interpolates between points for smoother plots.

Why other options are incorrect:

• (A) Resolution increases, not decreases, with zero-padding.
• (C) Padding increases the length of the data, potentially increasing computation, not reducing it.
• (D) Zero-padding does not affect the amplitude of components; it interpolates the spectrum.